The present invention relates to a photovoltaic cell product and a method for its manufacture.
Photovoltaic devices or solar cells absorb sunlight and convert it directly into electrical energy. The basic scientific principles which underlay the effect of converting light energy into internal voltages using photovoltaic cells are well understood.
Most types of photovoltaic cells have a photoactive area, i.e., an area that generates electricity in response to light and is composed of a semiconductor layer disposed between two electrode layers deposited on a flat, supporting substrate. The photoactive area is divided into a number of photovoltaic cells interconnected in series to boost the voltage output. The photovoltaic cells may then be encapsulated, e.g. with plastic, to protect the cells from the external environment during transportation and operation of the cells. A number of electrically interconnected photovoltaic cells may be supported on a common rigid medium, such as glass, to form a photovoltaic module.
The process of sequentially forming photovoltaic layers onto a supporting substrate is a common technique for making xe2x80x9cthin film photovoltaic cells,xe2x80x9d also a well known product. Most thin film solar cells are deposited onto glass as part of the manufacturing process. However, the sequential deposition of layers on a rigid medium such as glass is expensive, cumbersome, not well suited to high speed operation, and often expensive to ship. Moreover, the plastic casing is expensive and it remains a failure point throughout the life of the photovoltaic cells due to the tendency of plastic to degrade in sunlight. Thus, there is a need for an improved process of making thin film cells which is more suitable for high volume production, increased life span, versatility of the product, and lower manufacturing and transport costs.
U.S. Pat. No. 5,674,325 issued to Albright et al. on Oct. 7, 1997 is an example of a method of manufacturing a thin film photovoltaic device. Albright et. al. describes a process involving a xe2x80x9csurrogate substratexe2x80x9d that is separated from film layers so that the film layers may eventually be incorporated into a photovoltaic cell to be supported on a permanent substrate. The Albright device does not have a permanent substrate onto which the photovoltaic material is deposited, rather it has a surrogate substrate. More importantly, the Albright device does not contain or suggest the use of a contact transfer release sheet as a top layer, over the thin film cells, or elsewhere. The same holds true for U.S. Pat. No. 5,868,869 issued to Albright et al. on Feb. 9, 1999. Other methods and devices similar to, or analogous with, thin film cells and their manufacture include U.S. Pat. No. 5,520,763 issued to Johnstone on May 28, 1996, which describes a manufacturing process in the printing art that uses a foil strip and a release sheet fed through a roller. Johnstone does not suggest the present method of making a photovoltaic device. U.S. Pat. No. 5,417,770 issued to Saitoh et al. on May 23, 1995 is a forming method used in the manufacture of a photovoltaic device. Saitoh et al. do not suggest the present method of making a photovoltaic device. U.S. Pat. No. 3,729,343 issued to R. D. Thomas on Apr. 24, 1973 describes a method of rolling a thermocouple tape. R. D. Thomas does not suggest the present method of making a photovoltaic device.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
The present invention is a photovoltaic device and method for its manufacture that facilitates packaging, transport and installation of solar panels and solar arrays. The manufacturing process incorporates a multi-vacuum-chamber system forming a thin film cell layer made from photovoltaic materials on a permanent substrate. The thin film cell layer is then binded to a contact transfer release sheet.
The photovoltaic materials includes: multiple p-i-n junctions, a Zno layer, film masked fingers, and continuous bus bars deposited along each of two edges of the thin film cell layer, one bar along a positively charged edge, and one bar along the negatively charged edge. Adhesion of the contact transfer release sheet to the thin film cell layer is also performed in a vacuum deposition chamber.
A roll of photovoltaic material is then segmented at intervals of at least three fingers, to produce thin film cell stickers, preferably about one inch by twenty-four inches in area. This product can be shipped directly to end users for on-site customization. Included in the method is a procedure for on-site customizing, wherein, the outer barrier layer of the release sheet is removed. The thin film cell stickers are then adhered, like the backing of a bumper sticker, to the underside of a translucent medium to form a solar panel.
The panel may be customized into a parallel circuit or a series circuit. Finally, a conductive foil strip interconnect clip is crimped to the adjacent bus bars of adjacent thin film cell stickers. The sun shines through the translucent medium (e.g., glass), hits the photovoltaic thin film cells, and electrical energy is drawn off by a conduit.
Accordingly, it is a principal object of the invention to facilitate compact packaging, and to reduce transportation costs by enabling photovoltaic devices to be shipped separately from any glass, aluminum frame, or any other typically heavy medium, thus reducing the weight and therefore the cost of shipping.
Still another object of the invention is to provide a process and a product that eliminates the need to encase thin film photovoltaic cells in plastic, which is costly.
It is yet another object of the invention to provide a photovoltaic product that minimizes the possibility of theft, vandalism, or damage from natural elements.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.